1. Field of the Invention
This invention relates to an electronic component-mounting apparatus of multi-function type for mounting various kinds of electronic components on a circuit board, and a mounting head device installed on the electronic component-mounting apparatus.
2. Prior Art
Conventionally, an electronic component-mounting apparatus of this kind has been proposed by Japanese Laid-Open Patent Publication (Kokai) No. 4-35095, which includes a sucking nozzle for sucking an electronic component, a mounting head carrying the sucking nozzle, an elevating device for vertically moving the sucking nozzle, and an X-Y stage for moving the mounting head in an X-axis direction and a Y-axis direction on a horizontal plane. Further, the electronic component-mounting apparatus includes a nozzle storage device for holding a plurality of kinds of sucking nozzles in stock for selective use to make the mounting head adapted to various kinds of electronic components. The mounting head carries a single sucking nozzle, which can be replaced at the nozzle storage device by one suitable for an electronic component to be mounted .
FIG. 1 schematically shows operations of the electronic component-mounting apparatus constructed as above. The figure illustrates a case in which an electronic component sucked at a point A of a component-feeding block 101 is mounted at a point P1 of a circuit board 102, and then an electronic component sucked at a point B of the component-feeding block 101 is mounted at a point P2 of the circuit board 102. First, the X-Y stage 103 moves the mounting head 104 from its home position to a position exactly above the point A, and then the elevating device 105 lowers the sucking nozzle to suck the electronic component at the point A. After sucking the electronic component, the elevating device 105 lifts the sucking nozzle, and the X-Y stage moves the mounting head 104 from the point A to a position exactly above the point P1. Then, the sucking nozzle is lowered again to mount the same at the point P1.
The mounting head 104 is then moved to the point B to suck an electronic component and mount the same at the point P2 of the circuit board 102. In doing this, if the same sucking nozzle as employed for the immediately preceding electronic component can suitably handle the present electronic component, the same procedure as described above is carried out to mount the electronic component. However, if the electronic component supplied at the point B cannot be handled by the same sucking nozzle, the mounting head 104 is once moved to the nozzle storage device 106, where the sucking nozzle is replaced by one suitable for the present electronic component. The mounting head 104 is then moved to the point B to thereafter carry out the same mounting operations as described above.
On the other hand, Japanese Laid-Open Patent Publication (Kokai) No. 5-226884 discloses an electronic component-mounting apparatus of rotary type, which includes mounting heads each carrying a plurality of sucking nozzles. The sucking nozzles of the mounting head are arranged along the circumference of the mounting head at equally-spaced intervals such that each of them is capable of projecting and retracting, and as a whole rotating about the vertical axis of the mounting head 104. The sucking nozzles are each urged by a coiled spring in a projecting direction, with an engaging member being arranged for an upper portion of each of the sucking nozzles for holding the same in a retracted position. Each engaging member is pivotally movable between a position for engagement with a sucking nozzle associated therewith and a position for disengagement therefrom, and urged by a spring in an engaging direction.
That is, when each sucking nozzle is retracted against the urging force of the coiled spring, it is brought into engagement with the engaging member to be held in the retracted position. Inversely, when the sucking nozzle is disengaged from the engaging member, it is brought into a projected position by the coiled spring. Therefore, in changing (replacing) sucking nozzles, the mounting head is lowered to cause the sucking nozzle to strike against a flat stopper whereby all the sucking nozzles are once retracted, and then as the mounting head is lifted, an arm extending from the body of the apparatus prevents engagement of a selected sucking nozzle with an engaging member associated therewith.
In the conventional electronic component-mounting apparatus, as more kinds of electronic components are to be mounted on one circuit board, sucking nozzles are changed more often. In other words, the mounting head 104 is more frequently moved to the nozzle storage device 106 for replacement of sucking nozzles. Particularly, it takes time to change sucking nozzles since it involves moving of the mounting head 104 before the sucking nozzle is removed therefrom and a new sucking nozzle is mounted thereon, so that, as a whole, the tact time of mounting electronic components on the circuit board 102 is increased.
Further, in the mounting head used in the electronic component-mounting apparatus disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 5-226884, the stopper is necessitated for changing sucking nozzles, and horizontal motion of the mounting head has to be interrupted so as to lower the mounting head and then lift it up.